The present invention relates to an interlocking construction in a transmission manipulation device for manual transmission and, more particularly, to an interlocking construction which is intended for holding immovable shift forks which are not to be shifted in the shifting operation of the transmission.
A typical conventional transmission manipulation device has a plurality of shift forks mounted axially movably on a fork shaft which in turn is fixed to the transmission case, and a shift and select lever shaft which is mounted in the transmission case at a right angle to the fork shaft. In the manipulation of the transmission, the selecting operation is effected by axial movement of the shift and select lever shaft to bring the engaging portion thereof into engagement with one of the shift forks, while the shifting operation is effected by the movement of the shift fork on the fork shaft upon rotation of the lever shaft. The interlocking construction in this type of transmission manipulation device is required only to hold immovable the shift forks which are not to be shifted in the shifting operation of the transmission shaft. This interlocking construction, however, cannot be applied to the transmission manipulation device to which the present invention pertains, as will be understood from the following description.
The manipulation device for transmission to which the present invention pertains has a first fork shaft and a second fork shaft parallel to each other and axially movably carried by the case of the transmission. The first fork shaft carries a plurality of shift forks axially movably and rotatably. The shift forks have engaging portions aligned in the direction perpendicular to the fork shaft. The transmission case carries also a shift and select lever shaft perpendicular to the fork shafts for axial movement and rotation. The lever shaft is provided with a first projection capable of selectively engaging the engaging portion of one of the shift forks. A first shift head having an engaging portion, which is in a side-by-side relation to the engaging portion of the shift forks, is fixed to the first fork shaft. The lever shaft is provided with a second projection capable of engaging the engaging portion of the first shift head only when the first retaining portion is in engagement with the engaging portion of one of the shift forks on the first fork shaft. At the same time, a single shift fork is fixed to the second fork shaft. Also, a second shift head having an engaging portion in a side-by-side relation to the aforementioned engaging portions is fixed to the second fork shaft. The first projection of the lever shaft is selectively engageable with this engaging portion.
Therefore, when the fork shaft, particularly the second fork shaft, is shifted, it is necessary to hold immovable not only the shift forks on the first fork shaft but also the first fork shaft itself. This can hardly be achieved by the conventional interlocking construction explained before.